Circuit interrupter



sept 20, 1938. J. sANDlN 2,130,904

CIRCUIT INTERRUPTER Filed Sept. 27, 1935 I5 Sheets-Sheet l BY GMW' W ATTORNE Sept. 20,` 1938. 1 SANDlN 2,130,904

CIRCUIT INTERRUPTER WITNESSES: NVENTOR r u TORNE Patented Sept. 20,

CIRCUIT INTEBBUPTER Jerome Sandin, Forest Hills, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 27, 1935, Serial No. 42,395

25 Claims.

My invention relates generally to electrical apparatus and more particularly to electro-responsive trip devices for use in conjunction with circuit breakers of the type used for controlling distribution network and industrial feeder circuits.

'Ihe provision of a satisfactory circuit interrupter for this type of service has always presented a most troublesome problem to the art, due to the exacting and somewhat conilicting requirements which a commercially successful device must meet. Because of the large amounts of power which may be fed into a short, circuit or other fault conditions on circuits of this type, it is necessary that the protective breakers therefor shall be capable of reliably interrupting extremel" large amounts of power, despite the fact that the normal current flow through the circuit and hence the normal current rating of the breaker does not exceed more than a moderate value. Further, in-order to preserve system stability, it is necessary that the interrupter shall be capable of interrupting these large amounts of power within an extremely short interval of time.

Breakers of the type to which the present invention particularly appertains are usually operated by more or less inexperienced persons, and they are often mounted in exposed locations indoors. As a result, it is imperative that they shall be absolutely safe and reliable in operation.

To assure adequate protection of the associated equipment, it is necessary that the breakers shall be capable of automatic operation in response to the actuation of a trip device or like means responsive to overloads or other abnormal circuit conditions. Further, it is desirable that the electro-responsive trip means for eiecting automatic operation of the breaker shall be capable of accurately distinguishing between transient overloads and those of a prolonged character, because if the interrupter shall operate immediately upon the occurrence of all overload conditions, it is inevitable that there will be numerous unnecessary and undesirable discontinuities in the service.

In contrast with these operational requirements, it is essential that the initial cost of the breakers shall not be unreasonably large, due to the large number which are used on even a small system or network. Likewise, if the device is to be commercially successful, it is necessary that the servicing and maintenance costs shall not be unduly large.

The principal object of the present invention, therefore, is to -provide an improved circuit (Cl. 20o-116) breaker and trip device which shall be capable of meeting all of the above stated requirements.

One form of circuit breaker which has been used rather extensively in the past, comprises a standardized contact structure and actuating mechanism, a suitable closure, terminals for connecting the breaker into an electric circuit, and a removable, electro-responsive trip device operable upon the occurrence of predetermined conditions to cause the actuating mechanism to move the contacts automatically to the open circuit position. By making the trip device readily removable and hence interchangeable withy similarly proportioned devices of like or different rating, it is possible to market an entire line of circuit breakers built up around a single, standardized contact structure, actuating mechanism, and breaker closure. This arrangement obviously makes possible substantial reductions in the initial cost of the apparatus, and by greatly reducing the number oi-parts which must be stocked by both the manufacturer and the user, it also decreases the operating and maintenance costs.

Since the trip devices are removable as a unit from operative engagement from the other elements of the breaker structure, it is necessary that some means be provided for preventing unauthorized persons from tampering with the mechanism of the trip device or altering the calibration thereof. The usual means for accomplishing this consists in the provision of a separate sealed closure for the trip device, this closure forming an integral part of that device.

While the use oi a sealed closure for the trip device constitutes a satisfactory means for preventing tampering with the mechanism of the trip device, it has the objection that it does not permit any change to be made in the tripping point of the trip structure during the operation thereof. The provision of means whereby the tripping point of a trip device which is provided with a separate, sealed closure may be varied constitutes another, and possibly the most important, object of the present invention.

A further object of the present invention is to provide a simple means for adjusting the tripping point of the electro-responsive tripping elements of a trip device of the above described type, which means may be calibrated during the manufacture of the device and which is so arranged that it will not ordinarily getout of adjustment or otherwise lose its calibration during its operative life.

A still further objectief the invention is to provide a simple means for varying the tripping point;

of a removable, unitary trip device, which means shall include latching means for positively retaining the adjusting means in any position to which it may be moved.

an ancillary object o the invention is to provide a simple and reliable means for altering the tripping point of electro-responsive trip devices of the type under consideration, which means may be readily embodied into existing structures without substantial modication thereof.

rFliese and other obj cets oi the invention will i made more apparent in the drawings and the iollo ving description of one preferred embodii it "-iereoi. Referring particularly to the drawings,

Figure l is a plan view of a circuit breaker which is provided. with a removable trip device coi'rstructed in accordance with the present in vention.

lg. 3 is a plan view of the removable den vice fo' g a part of the b eaker illustrated in l and 2.

l is an enlarged sectional view ci the trip e shcvm particularly in Fig. S. The view is on the line 'i-i of that igure.

li a ragmentary plan view of the trip e illustrated in Figs. 3 and The view is take' line 'if-i7 of Fig. Fi d is a fr gmentary perspective view showing he features of the trip device illustrated in the other- Figures of the drawings and the aol-- justing means used in conjunction therewith.

iig. 7 is an exploded perspective view of the adjusting means utilized for altering the tripping point oi the thermally responsive tripping elements forming a part of the trip device shown in detail in the other figures of the drawings.

Fig. 8 is a fragmentary iront elevational view eti devi

devi

oi the trip device illustrated particularly in Figs.

3 through 6, and

Fig. 9 isa fragmentary view similar to 'Eig'. l showing the structuralfeatures of the trip device in a position intermediate the normal inoperative and the operative position.

The circuit breaker shown in Figs. l and 2 is of the three-pole type and comprises, generally, a cooperating base l and cover 3 which dene the breaker closure; six terminals 5, two for each of the three poles, for connecting the breaker into electrical circuit or circuits; three stationary contacts l; three movable switch arms Si, each to the movement oi a suitable operating handle iti to move the switch arms e and the movable contacts il into and out or" engagement with the stationary contacts l; and an electro-responsive trip device lll operable upon the occurrence of predetermined conditions to cause the actuating mechanism i3 to move the switch arms il and the movable contacts ll associated therewith automatically from the closed circuit position to the open circuit position. The base l and the cover 3 are preferably formed of molded insulating material and are provided with suitable cooperating ribs and partitions I9 molded integral therewith for dividing the breaker closure into three separLe cover portion oi the breaker closure areas-cc rate chambers, one for each of the poles of the breaker.

is will be discussed in detail in subsegu nt paragraphs, the trip device il is removable as unit from operative engagement with the other elements of 'the breaker. It is provided with a sealed closure, a plurality of electroeresponsivc `ipping elements, each individually actuable to eiect the operation of the trip device, disposed within the closure, and means for varying tripping point oi" at least some of the elements w hout necessitating the openi the sealed closure.

@ne of the tern nals e7 is mounted at either end of each of the th ee pole chambers dened b' "he partitions L79 by means of suitable screw ia. ings. lThe station y Contact 'l oi' each o poles oi the breaker is supported upon flat strip oi conducting aterial which is rigidly Hed to the base of the interrupter, adjacent the upper end of each oi the gole chambers, by suitable screws or like means; each of the strips fil also serves to electrically connect the stationary ereon with the coopera" the breaker. Each of as a flexible shunt tei te crazed to the central porone of these shunts 2 serves the movable contact inemi the terminals oi the re movable trip device The corresponding c posite terminal of the removable trip device il' is directly connected to one oi the lower terminals oi the breaker, and a looped conducting strip f which serves as the energizing means for tripping elements associated with each pole of the trip device serves to complete the electrical circuit for each of the poles of the breaker between each oi the cooperating pairs of terminals till of the trip device. Each of the movable contacts il is resiliently biased toward the cooperating stationary contact "l by a dat leaf spring 2G.

The three switch members il are mechanically interconnected by means of a square tie member Eil of insulating material7 which member is rigidly anixed to the rear portion oi the frame 3l of each of the switch arms 9. The assemblage formed by the three interconnected switch arms il is pivotally supported upon the frame of the actuating mechanism i3 by means of a suitable pivot pin 35.

The actuating mechanism i3 for the breaker is not an important part of the present invention and any means whereby the interconnected switch arms il and the movable contacts ll associated therewith may be moved to the open and to the` closed circuit position in response to movement of an operating handle, and whereby automatic opening ci the breaker isefected in response to the operation of the breaker trip device may be employed. i prefer to use a mechanism of the type disclosed in the copending application of Harry J'. Lingal, Serial No. 600,624, which was led on March 23, 1932, now Patent #2,047,739, issued July 14, 1936, and which is assigned to the assignee of the present invention.

A mechanism of this type, as is shown particularly in Fig. 2, comprises the operating handle l5, a pair of'interconnected link members 31 and 39 which form a toggle linkage, and an overcenter spring il for operatively connecting the toggle linkage with the operating member l5. One end of the toggle linkage is mechanically connected to the frame 3l or the central switch member or otlierwise hereof,

-ect each of with one ci fg. il

by a pivot pin 43, and the other end of the toggle 75 linkage is supported upon a cradle member 45 which member is, in turn, supported on the frame 33 of the actuating mechanism by a pivot pin 45. The cradle member 45 is normally restrained in the position shown in Fig. 2 by the latch means 41 forming a part of the trip device I1.

41 releases the unsupported lower end of the cradle 45, and that member moves under the biasing action of the reaction force of the overcenter spring 4I in a counterclokwise direction about the supporting pivot pin 46 therefor to a position where the center line of the overcenter spring 4I lies beneath (Fig. 2) the center line oi the link 31. In this position, the toggle linkage is unstable, and it is moved to the collapsed position by the overcenter spring 4I, thereby eecting the movement of the interconnected switch arms 9 to the open circuit position. The mechanism is so arranged that the cradle member 45 may be restored to the latched position by moving the operating handle I5 from the position shown in Fig. 2 to the normal open circuit position.

The trip device I1, as mentioned in the foregoing, comprises a unitary structure having a base 5I and a cover 53 -for cooperating therewith to define a closure for the device, the six terminals 25 for electrically connecting the trip device into the 'circuit controlled by each of the poles of the breaker, the latch means 41 which cooperates with the contact actuating mechanism I3, a plurality of electro-responsive tripping elements each operable upon the occurrence of predetermined conditions to effect the operation of the trip device, thereby causing the latch means 41 to release the cradle member 45, and means for adjusting the tripping point of at least some of the electro-responsive elements. The base 5I and cover 53 are preferably formed of molded insulating material and the terminals 25 are rigidly ailixed to the base 5I in order that they may serve to support the trip device within the breaker closure when that device is in an operative position therein.

The trip device I1 includes three thermally responsive and three magnetically responsive tripping elements, and these tripping elements are arranged in pairs, consisting of one element of each type. The two component elements of each l oi' these pairs are supported upon a common let frame 54 which is afxed to the base 5I of the trip device by two screws .55, and are energized `in response to the current flow in one of the poles of the breaker. Each of the thermally responsive tripping elements comprises a bimetallic strip 51 which is riveted at one end thereof to one of the looped conductors 21 and to the central portion of one of the common support frames 54 which serve to support each pair of the tripping elements. The conductors 21 are provided with suitable portions Aof increased resistance in order that they shall serve as energizing heaters for the thermally responsive elements. A single trip bar 6I, which is formed of molded insulating material and which is pivotally supported at the ends thereof as shown at 62, extends across the entire trip device and hence across all of the poles of the breaker. This bar is adapted to be engaged and moved from the normal inoperative position, as shown in Figs. 4 and 6, to a position where it effects the operation of said trip device by any one of the tripping elements. The trip bar 6I is provided with a latch retaining member 53 rigidly Uponn the operation of the trip device this latch means' supported thereon for engaging the pivoted trip latch 65, and is biased into engagement with this latch by a suitable springl 81 interposed between the base 5I of the trip device and a projection 69 molded integral with the trip bar. The trip latch 55 is pivoted as shown at 66.

Each of the magnetically responsive elements comprises an amature 1I supported for slidable movement upon a suitable bracket 13 formed integral with the supporting frame 54 for each pair of the tripping elements. Each of the armatures 1I is biased to the position shown in Figs. 4 and 6 by means of a suitable spring 15, and the support and guide pin 11 for each of the armatures is provided with an enlarged head portion 18 for directly engaging suitable cooperating openings formed in the trip bar 5I. A U-shaped core 3| is supported upon each oi' the frames 54 for attracting the armature 1I of each of the magnetically responsive elements, and the looped conductor 21 for each of the poles of the trip device extends through this core in order that the energization thereof shall be responsive to the magnitude of the current owing'through each of the poles of the breaker.

As mentioned above, each of the looped conducting strips 21 has a portion of reduced cross section disposed adjacent the portion thereof which extends along the associated bimetallic member 51, and the constants of the several structural features are so arranged that the heating produced by thevflow of predetermined abnormal currents through any one of these conducting strips for a predetermined period of time results in sufficient heating of the associated bimetallic member 51 to cause that member to move from the normal position shown in Fig. 4 to a position where the latch engaging member 63 disengages the trip latch 65 thereby effecting the operation of the trip device, and the opening of the breaker. The position of the elements of the trip device shortly before the latch engaging member 63 has disengaged the trip latch 65 are illustrated in Fig. 9.

Upon the occurrence of predetermined large overloads in the circuit controlled by any one of the poles of the breaker, the core member 8| for the corresponding pole of the trip device is energized sufilcientiy to attract the associated armature 1I thereby moving the trip bar 6I to the tripped position. Thus, the trip device is operable after a. predetermined time interval following the occurrence -of predetermined low magnitude overloads to cause theactuating mechanism I3 to eiect the opening of the breaker, and it is operable substantially instantaneously upon the occurrence of predetermined large magnitude overloads to effect the opening of the breaker.

The above stated mode of operation provides satisfactory protection for a large number of present day installations. However, in certain instances, it is desirable to vary the tripping point of the thermally responsive elements either to take care of certain temporary abnormal conditions or to provide a more flexible arrangement. The provision of means for accomplishing this,- without necessitating the opening of the trip closure, constitutes, as mentioned previously, one of the most important objects of the present invention.

As shown particularly in Figs. 4 through 7, each of the bimetallic, thermally responsive elements 51 engages the trip bar 6I through an adjustable engaging means. Generally, this means comprises an adjustable screw disposed intermediate the trip bar @l and the bimetallic element 5i, means ior holding the screw -in predetermined positions, a suitable calibration scale, and an operating member iii).

More particularly, each of the adjusting means is mounted upon a frame member which slidably engages the upper portion of the trip bar 6 l rlhe adjustable screw 83 for directly engaging the bimetallic elements is adapted to extend through a suitable threaded sleeve 8l molded integral with the trip bar itself, and is preferably a multithread screw in order to maximize the longitudinal movement thereof in response to movement of the operating member @il for the adjusting means. rl'he operating member is formed o insulating material and is rigidly connected to the adjustable screw 33 by means of a locking screw Qi which extends through an opening i3 formed therein. in order that the adjusting means shall retain my particular setting, a notching member 95 is positioned intermediate the supporting frame 85 and the operating member e9, this member being mechanically connected to the operating member by means oi a suitable screw Q'l. Each of the operating members 89 extends through an opening 98 formed in the cover 5S of the trip device, in order that the tripping point of the bimetallic tripping elements may be varied without necessitating the openin of the closure ior the trip device.

Each'oi the frames is provided with a pair of tooth-like projections 99 formed integral therewith for engaging similarly proportioned, radially extending teeth itl formed in the upper portion M12 of the intermediate member 95 which is supported thereon, and a suitable spring M33, which is positioned between the central portion of the supporting frame 85 and the trip bar 'i l, serves to bias the cooperating toothed portions 99 and lli of the intermediate member and the frame into resilient engagement with each other. The frames 8b are provided with openings @t through which the adjusting screws 83 pass, the openings t6 being of slightly greater diameter than the diameter of the screws 83 as shown in Fig. 7. The top flanges Si! of the members 85 rest on the top surface of the trip bar lill. The frames 85 are free to slide in an axial direction on the adjusting screws 83 and are held against rotational movement thereon by reason of the springs M33 which obviously hold the lower fiat surface of the flanges 88 in frictional engagement with the top surface of the trip bar 6l. The frames 35 are biased by the springs H33 so that the depending anges Elli which carry the teeth 99 are biased into resilient engagement with the surface of the intermediate members which carry the teeth lili. The members 95 are held in rigid engagement with their operating members 89 by the screws Q'l to turn with the same, and the operating members are thus resiliently retained in any set position by the resilient engagement of the teeth 99 with the teeth lill. A suitable calibration scale is engraved on the exposed face of each of the frames t5. In the structure illustrated in the drawings a scale having three calibration points, representing 80, 100, and per cent of the normal rating of the bitmetallic tripping elements, has been provided for each adjusting means.

W hen these devices are being manufactured on a production basis, the calibration scales for any particular range of current values are uniform.

t is necessary, therefore, that the adjusting screw 33 for each of the adjusting means shall be accurately positioned with respect to the co-operating notching member Sii during the assembling operation. IThis positioning is preferably accomplished by setting the notching member Q5 to some point on the calibration scale, then adjusting the screw S3 to a position where the operation ci the trip device will be in response to a current value corresponding to the selected point on the calibration scale, and finally soldering or otherwise locking the screw and notching member in the determined position. -lifter this has been done, the operating member 89 may be a'- xed to the interconnected screw and notching member without danger that the calibration shall be disturbed.

A pair of projecting lugs lli?) are formed integral with the supporting frame S5 for each oi the adjusting means and are adapted to engage the downwardly projecting portion Wl or intermediate notching member in order to provide stops for preventing the operating member G9 from being turned more than about during the adjusting operation. This means assures that the'accuracy of the calibration scales Shall not be impaired due to the turning or the operating member 39 completely around.

lt is believed that the operation ci the breaker actuating mechanism and the trip device i'l is obvious from the foregoing. The actuating mechanism i3 is operable to move the assemblage termed by the interconnected switch arms Si from the closed circuit position shown in 2 to the open-circuit position in response to movement of the operating handle l5. any one of the bimetallic thermally responsive tripping elements 5"] or themagnetically responsive tripping elements is actuable upon the occurrence oi predetermined conditions to effect the operation oi the trip device lll, i. e., to move the trip bar 6l from the normal inoperative position shown in Fig. l to an operative position, in which latter position the latch retaining member G3 is moved out of engagement with the pivoted trip latch 65. When this occurs, the latch 65 is free t0 rotate in a clockwise direction. The latch 65 is partially rotated in a clockwise direction against the action or its return spring H36 by the movement of the cradle member 45 eiected by the tension of the switch actuating overcenter spring lll, whose tension is greater Ythan that of the return spring H06. The movement of the cradle member 45 continues after its nose has passed beyond the depending end of the latch 65. At this point the spring IBB which biases the latch in a counterclockwlse direction returns the latch E5 to its latching position where it is again in position to automatically reengage the nose of the cradle member when said cradle member is returned to latched position upon the manual movement o1 the handle l5 to open position. Following its release, the cradle member l5 moves automatically under the reaction forces ol the overcenter spring [ll to a position where it eiects automatic operation of the actuating mechanism i3 and the opening of the breaker. rThe overcenter spring construction of the breaker actuating mechanism causes the assemblage formed by the interconnected switch arms 9, and hence the movable contacts il, to be moved from one position to the other with a snap action.

rThe latch 55 is biased to the normal latched position shown in Fig. li by the return spring 10b, and the trip bar Si is also biased to the normal inoperative position shown in Fig. l by the spring rThe latchv (i5 is provided with a biiurcated end Gi@ which pivotally engages the pivot pin 66.

The return spring has a bent end |08 which engages a notch provided in an edge of the latch 65 at a point above and to the right of the pivot pin 65 as best shown in Fig. 4. The body of the spring is then coiled around the pivot pin 56 and its other end engages under tension the top of the base of the yoke which supports the pin 00 as clearly shown in Figs. 4 and 5. The latch 65 is thus rotatably mounted on the pin 56 and is also free to slide thereon by reason of the bifurcated end 58. After the latch 65 has been released and the cradle member I5 moves to open the contacts, the spring |06 returns the latch to latching position as explained above. When the cradle member 45 is now rotated in a clockwise direction, by operation of the switch handle I5 to the open position, the cam surface of the nose of the cradle causes the latch 55 to partially slide back on the pivot pin 66 and thus allows the nose to move past the latch engaging portion 10. The cradle is now again in latched position. 'I'hus the trip device is automatically re-settable following each operation thereof.

To reset the operating mechanism I3 following each automatic operation thereof, the operating handle I5 is moved from the intermediate tripped position to the normal open circuit position. 'I'his movement is transmitted directly to the cradle member 45 and that member is returned to the position shown in Figs. 2 and 4. In order to permit the trip latch 65 to reengage the cooperating end of the cradle member 45 during the resetting operation of the mechanism I3, the latch 65 is slidably as well as pivotally mounted upon the support means therefor as has been previously explained.

It will be seen that the above described means constitutes a simple, accurate, and convenient arrangement for yvarying the tripping point of the bimetallic tripping elements 51 from without the sealed closure for the trip device. While a variation between 80 and 120 per cent4 of the normal rating of the tripping elements is ordinarily sufilcient and such a calibration scale of this range has been illustrated in the drawings, scales of other ranges may be readily provided. The downwardly projecting portion I0`I of the intermediate notching member which engages the stops |05 comprises a convenient indicator for cooperating with the calibration scale.

In th'e assembled trip device the notching means forming part of each of the tripping point adjusting means retains the operating member 89 in any position to which it may have been moved and thus renders the device reliable in operation. The lugs or stops |05 which prevent the operating members 09 for the adjusting means from being moved beyond the normal operative range of the device add a. further factor of safety.

Ordinarily, the trip device will be calibrated during its manufacture. 'I'he cover 53 will then be placed in cooperative engagement with the base 5I and will be alllxed to the brackets |08, which also serve to support the trip bar 6I by means of suitable screws |09. Them-to prevent tampering with the device, a seal III will be placed over each of the screws, as is shown parl ticularly in Figs. 3 and 8. The resultant trip device comprises a unitary structure, all of the operative elements of which are enclosed within a sealed closure. At the same time, the tripping point of any one of the thermally-responsive tripping elements 51 of the trip device may. without necessitating the opening of the sealed closure for the trip device proper, be varied within certain dennite limits by the movement of a suitable operating member. The objects of the invention are thus accomplished without any sacrice of the normal reliability of operation of trip devices of the type to which the invention particularly appertains, or without necessitating the provision of a device which is not sealed during its manufacture.

Further, the adjusting means of my invention is readily applicable to existing structures, bothl of the type which utilize separate sealed closures for the trip device and of the type which do not utilize such closures, without necessitating any vchange in their structural arrangement or physical dimensions. The entire adjusting means is supported upon the trip bar; while simple in structure, it is of substantially foolproof construction; and it is provided with 'a simple notching device for assuring that it shall retain its adjustment during the operation thereof.

If desired, suitable openings may be provided in the cover 3 for permitting the operating member 89 of each of the adjusting means to be reached and actuated from without the closure for the breaker proper.

While, in accordance with the patent statutes, I have disclosed the specic details of one embodiment of my invention, it is to be understood these details are merely illustrative and that variations in their precise form will be not only desirable but necessary in certain instances. It is my desire, therefore, that the language of the accompanying claims shall be accorded the broadest reasonable construction and shall be limited only by what is expressly stated tirarsi. and by the prior art.

I claim the following as my invention:

1. In a circuit interrupter, separable contact means, actuating means for moving said contact means to open and to close the electrical circuit through said interrupter, and a trip device operable upon the occurrence of predetermined conditions to cause said actuating means to move said contact means automatically to the open circuit position, said trip device being removable as a. unit from operative engagement with the other structural elements of said interrupter, and including a sealed closure, electro-responsive tripping means actuable to eilect the operation thereof and means carried by the trip device including a movable operating member insulated from the circuit for varying the tripping point of said tripping means within predetermined limits, said operating member being operable from outside said sealed closure.

2. In a circuit interrupter, a main closure, separable contact means disposed within said closure, actuating means also disposed within said closure for moving said contact means to open and to closev the electrical circuit through said interrupter, and a trip device operable to cause said actuating means to move said contact means automatically to the open circuit position, said trip device being removable as a unit from operative engagement with the other structural elements of said interrupter and including a closure separate from said main closure, electro-responsive tripping means actuable upon the occurrence of predetermined conditions to eiect the operation of said device disposed within said separate closure, terminals extending outside said separate closure for connection in the circuit through the breaker and adjustable means, which is actul able from without said separate closure, for vary- CII ing the tripping point of said electro-responsive means Within predetermined limits.

3. In a circuit interrupter, separable Contact means, actuating means for moving said contact means to open and to close the electrical circuit throughsaid interrupter and a trip device oper able upon the occurrence of predetermined con ditions to cause said actuating means to move said contact means automatically to the open circuit position, said trip device being removable as a unit from operative engagement with the other structural elements of said interrupter, and including a sealed closure, electro-responsive tripping means, actuable to effect the operation of said device, disposed within said closure, and means whereby the tripping point oi said tripping means may be varied without necessitating the opening of said sealed closure.

4. In a circuit interrupter, separable contact means, actuating means ior moving said contact means to open and to close the electrical circuit through said interrupter, and a trip device operable to cause said actuating means to move said contact means automatically from one position to the other, said trip device including a trip bar, movable from a normal inoperative to an operative position to efect the operation oi said device, electro-responsive tripping means actuable upon the occurrence of predetermined conditions to move said trip bar from said inoperative to said o erative position, and means which is entirely supported upon said trip bar for varying the tripping point of said electro-responsive tripping means `Within certain dened limits, said last mentioned means including a movable operating member and notching means for controlling the movement or" said member.

5. in a circuit interrupter, separable contact means, actuating means for moving said contact means to open and to close the electrical circuit through said interrupter, and a trip device operable to cause said actuating means to move said contact means automatically from one position to the other, said trip device including a pivotally supported trip bar which is movable from a normal inoperative to an operative position to eiect the operation of said device, electro-responsive tripping means actuable upon the occurrence oi predetermined conditions to move said trip bar from said inoperative to said operative position, and means which is supported on said trip bar so as to be disposed intermediate said bar and said tripping means for varying the tripping pint oi said tripping means Within certain dened limits, said last mentioned means including a,

rotatable operating member, screw adjusting means adapted to be operated thereby, and notching means for controlling the movement o1 said operating member.

6. ln a circuit interrupter, separable contact means, actuating means for moving said contact means to open and'to close the electrical circuit through said interrupter, a trip device operable to cause said actuating means to move said con-a tact means automatically from one position to the other, said trip device including a sealed closure, a trip bar which is disposed Within said closure and which is movable from a normal inoperative to an operative position to eifect'the operation of said device, electro-responsive tripping means which is also disposed within said clowre and which is actuable upon the occurrence of predetermined conditions to move said tripbar from said inoperative to said operative position, and means actuable from without said sealed closareas-oa ure for varying the tripping point of said electron responsive means Within certain deiined limits.

7. In a circuit inter^upter, a main closure, sepan rable contact means disposed within said closure, actuating means also disposed Within said closure for moving said contact means to open and to close the electrical circuit through said interruptor, and a trip device operable to causo said actuating means to move said Contact means automatically to the oprn circuit position, said trip device being removable as a unit from operative engagement with the other structural elements of said interrupter and including closure separate from said mabL closure, a trip bar which is disposed within said separate closure and which is movable from a normal inoperative to an operative position to effect the operation of said de vice, electro-responsive tripping means which also disposed within said closure and which is actuable upon the occurrence oi predetermined conditions to move said trip bar from said inoperative to said operative position to effect the operation oi said device, terminals extending outu side of said separated closure for connecting the tripping means in the circuit of the breaker and adjustable means, which is actuable from without said separate closure for varying the tripping point oi said electro-responsive means Within pre-w determined limits.

8. in a circuit interrupter, separable contact means, actuating means ior moving said contact means to open and to close the electrical circuit through said interrupter, a trip device operable to cause said actuating means to move said con tact means automatically from one position to the other, said trip device being removable as a unit from operative engagement with the other structural elements of said interrupter and including a sealed closure, a trip bar which is disposed Within said closure and which is movable from a normal inoperative to an operative position to effect the operation oi said device, electro-responsive tripping means Which is also disposed Within said closure and which is actuable upon the occurrence of predetermined conditions to move said trip bar from said inoperative to said operative position, and adjustable means `which is actuable from Without said sealed closure and which is supported on said trip bar for varying the tripping point of said tripping means within predetermined limits.

9. in a circuit interruptor, separable Contact means, actuating means ior moving said contact means to open and to close the electrical circuit through said interrupter, a trip device operable to cause said actuating means to move said contact means automatically from one position to the other, said trip device being removable as a unit from operative engagement with the other structural elements or said interrupt-er and in cluding a sealed closure, a trip bar which. is pivotally supported Within said closure and which is movable from a normal inoperative to an operative position to effect the operation of said device, electro-responsive tripping means which 1s also disposed within said closure and which is actuable upon the occurrence of predetermined conditions to move said trip bar from said inoperative to said operative position, and adjustable means which is actuable from Without said sealed closure for varying the tripping point of said tripping means within predetermined limits, said adjustable means including a movable operating member and notching means ior controlling the movement of said member.

10. In a circuit interrupter, a main closure, separable contact means disposed within said closure, actuating means also disposed within said closure for moving said contact means to open and to close the electrical circuit through said interrupter, and a trip device which is operable to cause said actuating means to move said contact means automatically to the open circuit position, said trip device including a closure separate from said main closure. electro-responsive tripping means which is disposed within said separate closure and which is actuable upon the occurrence oi predetermined conditions to effect the operation of said trip device, and adjustable means which is actuable from without said separate closure for varying the tripping point of said tripping means within predetermined limits, said adjustable means including a movable operating member and notching means for controlling the movement of said member.

11. In a circuit interrupter, a base, a removable cover for cooperating therewith to denne a closure for said interrupter, separable contact means disposed within said closure, actuating means, Llikewise disposed within said closure for moving said contact means to open and to close the electrical circuit through said interrupter, and a trip device operable to cause said actuating means to move said contact means automatically to the open circuit position, said trip device being normally disposed within said closure and including electro-responsive tripping means actuable upon the occurrence of predetermined conditions to effect the operation of said device and adjustable means including a movable operating member for varying the operating point of said tripping means within predetermined limits, said last-mentioned means being disposed within said closure and being so arranged that it may be reached and operated when said cover is removed from engagement with said base, and a notching means for releasably retaining said operating member in any adjusted position to which it is moved.

y means disposed within said closure, actuating means, likewise disposed within said closure for moving" said contact means to open and to close the electrical circuit through said interrupter. and a trip device operable to cause said actuating means to move said contact means automatically to the open circuit position, said trip device being normally disposed within said closure, and including a trip bar movable from a normal inoperativevto an operative position to eiect the operation of said device, electro-responsive means actuable upon the occurrence oi predetermined conditions to move said trip bar from laid inoperative to said operative position. and adjustable means including a movable operating member and notching means for controlling the movement of said member, for varying the operating point of said electro-responsive means within predetermined limits, said adjustable means being disposed within said closure, and being so arranged that said operating member may be reached and moved when said cover is removed from engagement with said base.

13. In a circuit interrupter, a base, a removable cover for cooperating therewith to denne a closure for said interrupter, separable contact means disposed within said closure, actuating means, likewise disposed within said closure for -Ior defining a plurality of poles,

moving said contact means to open and to close the electrical circuit through said interrupter, and a trip device which is normally 'disposed within said closure and which is operable to cause said actuating means to move said contact means automatically to the open circuit' position, said trip device being removable as a unit from operative engagement with the other structural elements of said interrupter and including electroresponsive tripping means actuable upon the occurrence of predetermined conditions to effect the operation of said device and adjustable means for varying the operating point of said tripping means within predetermined limits, said adjustable means including a movable operating member which is so arranged that it may be reached and moved when said cover is removed from engagement with said base, and a notching means for releasably restraining said operating member in any adjusted position to which it is moved.

14. In a circuit interrupter, a main base, a removable cover for cooperating therewith to deilne a closure for said interrupter, separable contact means disposed within said closure, actuating means, likewise disposed within said closure for moving said contact means to open and to close the electrical circuit through said interrupter, and a trip device which is normally disposed within said closure and which is operable to cause said actuating means to move said contact means automatically to the open circuit position, said trip device being removable as a unit from operative engagement with the other structural elements of said interrupter and including, a base, a trip bar supported on said base and movable from a normal inoperative to an operative position by a current responsive tripping means to effect the operation of said trip device, and adjustable means i'or varying the operating point of said tripping means within predetermined limits, said adjustable means including a movable operating member which is so arranged that it may be reached and moved when said cover is removed from engagement with said main base, and notching means for controlling the movement of said operating" member.

15. In a multi-pole circuit interrupter, a plurality of pairs of separable contact means for denning a plurality of poles, actuating' means for moving said contact means to open and to close the electrical circuit through the several poles of said interrupter, and a trip device oper- Y able to cause said actuating means to move said contact means automatically tothe open circuit position. said trip device including a trip bar which extends across a plurality of the poles of said interrupter and which is movable from a normal inoperative to an operative position to eil'ect the operation of said device, a plurality of electro-reponsive tripping means each of which is individually operable upon the occurrence of predetermined conditions to move saidv trip bar from said inoperative to said operative position, and a plurality of separate adjusting` means each of which includes a movable operating member and a suitable calibration scale for varying the operating point oi' each of a plurality of said electroresponsive tripping means within predetermined limits.

16. In, a multi-pole circuit interrupter, a plurality of pairs of separable contacts means actuating means for moving said contact means to open and to close the electrical circuit through the several poles of said interrupter, and a trip device operable to cause said actuating means to move said contact means automatically to the open circuit position, said trip device being removable as a unit from operative engagement with the other structural elements oi said. interrupter and including a base, a trip bar which. is supported thereon, which extends across a plurality or" the poles of said interrupter, and which is movable from a normal inoperative to an operative position to effect the operation of said device, a plurality of electro-responsive tripping means each of which is individually operable upon the occurrence o1 predetermined conditions to move said trip bar from said inoperative to said operative position, and a plurality of separate adjusting means each of which includes a movable operating member and a suitable calibration scale, both entirely supported on said trip bar, for varying the operating point 0; each oi a plurality of said electro-responsive tripping means Within predetermined limits.

17. In an electro-responsive trip device, a base member, a trip bar supported thereon, said trip bar being movable from a normal inoperative to an operative position to eect the operation orc said device, electro-responsive tripping means actuable upon the occurrence or predetermined conditions to move said trip bar from said inoperative to said operative position, and means which is entirely supported upon said trip bar for varying the operating point of said electroresponsive tripping means Within predetermined limits, said last-mentioned means including a supporting frame, a calibration scale, and. a rotatable operating member which includes an indicator ior cooperating with said calibration scale.

i8. In an electro-responsive trip device, a base, a trip member supported thereon, said trip member being movable from a normal position to a tripping position to eiect operation oi said device, electro-responsive tripping means operable in response to predetermined conditions to effect movement of said trip member to tripping position, a closure for said device, means including a movable operating member which is operable from outside said closure for varying the trip characteristic of said tripping means, and notching means for releasably retaining said operating member in any adjusted position to which it is moved.

19. In an electro-responsive trip device, a base, a trip member supported thereon, said trip member being movable from-a normal position to a tripping position to eiect operation or" said device, electro-responsive tripping means operable in response to predetermined conditions to effect movement of said trip member to tripping position, means for adjusting the tripping point of said tripping means including a movable operating member, and notching means for releasably holding said operating member in adjusted position.

2G. in an electro-responsive trip device ier a circuit breaker, a casing, tripping mechanism operable in response to predetermined conditions for operating said trip device mounted within aisaooe said casing, means including a movable operating member operable from outside said casing for varying the trip characteristic or" said device, and notching means for releasably retaining said operating member in any adjusted position to which it is moved.

2l. In a circuit breaker, relatively movable contacts, actuating means therefor, a trip device operable to cause said actuating means to move said contacts to open circuit position, said trip device including electro-responsive tripping means operable in response to predetermined conditions to ei'ect operation oi said trip device, adjusting means including a movable operating member for varying the tripping characteristic oi said tripping means within predetermined limits, and notching means for rcleasably retaining said operating member in any adjusted position to which it is moved.

22. In a circuit breaker, relatively movable contacts, actuating means therefor, a trip device operable to cause said actuating means to move said contacts to open circuit position, said trip device including electroresponsive tripping means operable in response to predetermined conditions to eiect operation of said trip device, adjusting means for the trip device including a movable ember adjustable Within predetermined iii-nits for varying the tripping characteristic of said tripping means, and means movable during the assembly and calibration oi the trip device for adjusting said limits.

23.111 a circuit breaker, relatively movable contacts, actuating means therefor, a trip device operable to cause said actuating means to move said contacts to open circuit position, said trip device including electroresponsive means to eirect operation or" said trip device, adjusting means for varying the trip characteristic or said trip device, said adjusting means being initially movable and then permanently set to permit operation of said trip device in response to one predetermined condition, and including a movable operating member movable at will after the device has been set to vary the trip characteristic oi the trip device a limited amount only relative to the permanent setting.

24. A trip device ror a circuit breaker comprising tripping mechanism operable in response to predetermined conditions to trip the breaker, adjusting means including a movable operating member adjustable within predetermined limits 

